Apparatus for removing a welding bulge from pipes

ABSTRACT

A welding bulge removing apparatus comprises a U-shaped carrier adapted to be placed by means of rollers on welded pipes at the weld bulge, and being provided with an arcuate guideway and a toothed segment. It also comprises a motor-operated carriage having a driving gear wheel and support rollers. Mounted on the carrier are cutting tool holders movable to and from the weld bulge. The gear wheel and the support rollers of the carriage are respectively brought into engagement with the toothed segment and the arcuate guide-way of the carrier. The carriage is adapted to be rigidly connected to a lifting mechanism of a vehicle used for raising and carrying the welding bulge removing apparatus, whereby rotation of the carrier is effected, while the carriage remains immobilized.

BACKGROUND OF THE INVENTION

The present invention is related to an apparatus for removing a weldingbulge, and in particular, to an apparatus for removing a welding bulgefrom resistance welded pipes while laying pipelines.

Variously constructed and modified apparatus for removing a weldingbulge, intended for operation in specific conditions, are well known inthe art.

The invention is directed to an apparatus designed for field operationwhile laying pipelines for the long-distance transporation of petroleumand gas. More specifically, the present invention deals with theapparatus designed for removing a welding bulge from resistance weldedpipes under the aforesaid conditions.

Apparatus thus far proposed, as exemplified in USSR Inventor'sCertificate Nos. 507373, 468729, 468730, generally comprise impact orcutting tools, motion and static parts, and mechanisms for driving thetools.

Such apparatus, particularly those intended for large-diameter (over1,000 mm) pipes, are of large dimensions and heavy weight, and thereforepresent problems in service and are greatly time-consuming for setupunder field conditions in pipeline construction. As a consequence, theirperformance has proved to be lower than that of the electric resistancewelding machines, which machines together with the apparatus in questionforming part of a single production complex.

Known in the prior art is an apparatus for removing a welding bulge fromresistance welded pipes as disclosed in USSR Inventor's Certificate No.589090. This apparatus comprises a U-shaped carrier adapted to be placedat the bulge zone in spaced circumferential relationship to the weldedpipes and it is provided with centering rollers, at least two of whichare radially movable with respect to the center of the welded pipescircumference and are generally disposed on the end portions of thecarrier, and cutting tool holders disposed on the carrier providemovement to and from the weld bulge.

The radially movable centering rollers are motor-operated, whereby thecarrier will be turned about the pipes at the weld bulge zone.

In operation, the motor-operated centering rollers by rolling over thepipes impart rotary motion to the carrier. As this takes place, theholders will perform the approach of the cutting tools to the weld bulgeand the carrier will provide the feed of this tool.

Though simple in construction, this apparatus will suffers from a numberof disadvantages.

Inasmuch as the motor-operated centering rollers of the known apparatusare supported upon the welded pipes, the reliability of the drive forfeeding cutting tools is completely dependent on the engagement of themotor-operated rollers with the surface of the pipe, providing the drivepower is sufficient to defeat resistance to the cutting tools.

The reliability of the roller-pipe engagement is in turn dependent onthe surface condition of the pipes and the rollers, since under fieldconditions there may be ice formation, oil film, and otherfriction-affecting deposition formations which can affect the frictionbetween the contacting parts. This brings about vibration in the toolsand a drop in the speed of feeding thereof, which in turn impairsperformance of the prior art apparatus. The problem of performance iseven more acute in view of the fact that the welding bulge has to beremoved in more than one pass.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an apparatus forremoving a welding bulge from resistance welded pipes, which is of asimple construction.

One more object of the present invention is to provide an apparatus ofthe kind specified, which exhibits a higher performance as compared tothat of the apparatus of a similar design.

A further object of the invention is to provide a more reliableapparatus for removing a welding bulge.

These and other objects of the invention, will become clear from thefollowing detailed description of an embodiment of the invention, whentaken in conjunction with the accompanying drawing, wherein an apparatusfor removing a welding bulge from resistance welded pipes comprises amotor-operated carriage adapted to be rigidly connected to a liftingmechanism of a vehicle used for raising and carrying the apparatus. Thecarriage includes support rollers and a driving gear wheel. Theapparatus further includes a U-shaped carrier having an arcuate guidewayand a toothed segment both adjacent the outer periphery of said carrierand extending the length thereof, and they are brought into engagementwith the support rollers and the driving gear wheel of themotor-operated carriage respectively. In operation, this arrangementprovides for rotation of the carrier, while the carriage remainsimmobilized.

The apparatus of the invention, being specifically adapted for anin-the-field operation while laying pipelines, provides for the requiredperformance and reliability as well as a higher quality surface afterbulge removal. In the course of test runs of the apparatus about 2000butt welds between pipes of a large diameter (1420 mm) were machined,the performance being 5 to 6 butt welds per hour.

BRIEF DESCRIPTION OF THE DRAWING

The nature and principles of the present invention will be understood byreference to the accompanying sole FIGURE of the drawing which showsdiagrammatically an apparatus of the invention as viewed along the axisof the welded pipes.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawing, the apparatus for removing a welding bulgefrom resistance welded pipes comprises a U-shaped carrier 1 adapted tobe placed at the weld zone in spaced circumferential relationship to thewelded pipes. The carrier is preferably of a disk-like shape having acentral opening 2 of a diameter, which complies with the abovecondition, and a slot 3 as wide as the diameter of the central openingso that the carrier 1 takes the form of a U with end portions separatedby a spacing or the slot 3 to pass the welded pipes therebetween inplacing the carrier 1 into position.

The carrier 1 is provided with centering rollers which are arrangedadjacent the periphery of the central opening 2 of the carrier 1 or theinner periphery of the same carrier. The centering rollers are mountedin pairs, of which rollers those designated by the reference numeral 4are made stationary with respect to the carrier 1 and are disposed onthe middle portion of the carrier, and those referred to as rollers 5are mounted for radial movement relative to the center of thecircumference of the welded pipes by means of hydraulic cylinders 6 andtogether with the hydraulic cylinders 6 are disposed on opposite endportions of the carrier 1. Also, the rollers 5 of one end portion of thecarrier 1 are so related to those of the other end portion that in theoperating position when the same are in contact with the pipe surface,the distance between them is less than the pipe diameter. It is to benoted that the number of the centering rollers is for illustrativepurposes only in that present disclosure and the one skilled in the artcan easily find some other solution as to the number of the rollers andtheir arrangement.

Mounted on the carrier 1 are two holders 7 for cutting tools, forexample milling cutters 8, each of the holders 7 being disposed atdiametrically opposite locations on the carrier 1. Each holder 7 is beltdriven from an electric motor 9 and together with the latter are mountedon a suspension member 10, which is articulated to the carrier 1 at 11.Each suspension member 10 apart from being articulated as shown in thedrawing at 11 is also connected to the carrier 1 via means providingradial movement, such as a hydraulic cylinder 12 mounted for moving theholder 7 to and from the weld bulge on the suspension member 10 swingingabout a link pin at 11. The suspension members 10 also carry formerrollers 13.

According to the invention, the carrier 1 is provided with an arcuateguideway 14 and a toothed segment 15, both being adjacent its outerperiphery. The apparatus is also furnished with a motor-operatedcarriage generally designated by reference numeral 16 and comprising aframe 17 supported by support rollers 18, a driving gear wheel 19 and anelectric motor 20 for setting in motion the gear wheel. In the drawing,the support rollers 18 and the driving gear wheel 19 are respectivelybrought into engagement with the arcuate guideway 14 and the toothedsegment 15, with the support rollers 18 being arranged and in engagementwith the arcuate guideway 14 at both sides the inner and outer thereof.

According to the invention, the carriage 16 is adapted to be rigidlyconnected to a lifting mechanism of a vehicle, such as a pipe layingcrawler-type machine, which may be used for raising and carrying thepresent apparatus.

For the purposes of this disclosure, "a rigid connection" is thought ofas the provision of a carriage which is stationary with respect to thewelded pipes at the zone of a weld bulge to be removed and this can beachieved by means of a link 21 and a suspension fixedly connected to avehicle boom designated by reference numeral 22 for the purposes ofillustration only.

OPERATION OF THE APPARATUS DESCRIBED

As previously stated, the apparatus of the invention may be moved by anysuitable vehicle, and with reference to one of the sequence of buttjoints in a pipeline which has been welded, the carrier 1 is placed atthe bulge zone on the pipes, such as shown in the drawing by referencenumeral 23. It is to be understood that the carrier 1 will be supportedby means of the centering rollers 4 and 5, the pipes having beenpreliminarily centered by the rollers 5 through the use of the hydrauliccylinder 6.

In operation, the milling cutters 8 in holders 7, which are set inrotational motion by the electric motors 9, approach the weld bulge bythe use of means in the form of hydraulic cylinders 12 so as to inciseor cut into an upset or bulge metal until the former rollers 13 comeinto contact with the surface of the pipes 23.

In this manner, the holders 7 are radially moved, i.e., the cuttingtools approach the weld bulge.

By switching on the electric motor 20 the gear wheel 19 is set in motionand rolls thereby over the toothed segment 15. Since the carriage 16 isstationary with respect of the pipe 23, the carrier 1 begins rotationabout the pipes. In this manner the cutting tools are fed along theentire circumferential weld of the butt joint.

The cutting tools are fed during one half of the rotation of the carrier1, inasmuch as one half of the rotation is sufficient for each of thetwo milling cutters 8 to machine half of the weld length, i.e. the wedbulge will be completely removed in half the rotation or one-halfrevolution of the carrier 1. It will be readily understood that byincreasing the number of cutting tool holders the length of feeds may bedecreased, which is in conformity with the principles of the presentinvention provided such increase in the number of holders does notunduly complicate the apparatus.

After the weld bulge has been removed, the cutting tool holders 7 aremoved from the surface of the pipes 23 with the help of the hydrauliccylinders 12, and the carrier 1, having made a reverse motion for halfthe rotation, again takes the initial position. Now, after the rollers 5have been removed off the pipe surface the apparatus is ready fortransfer to the next butt joint without any additional operations in thecase as the apparatus is dependent on electric and pressure sources fromthe vehicle.

As hereinabove disclosed, the apparatus of the invention is simple inconstruction, offers good service conditions, and is less time-consumingfor setups. This permits more efficient utilization of such apparatus inlaying pipelines.

While the invention has been described in terms of the preferredembodiment, numerous variations may be made in the apparatus illustratedin the drawings and herein described without departing from theinvention as set forth in the appended claim.

What is claimed is:
 1. An apparatus for removing a welding bulge fromresistance welded pipes, which comprises:a U-shaped carrier adapted tobe placed at the bulge zone in spaced circumferential relationship tothe welded pipes and having end portions spaced apart for the weldedpipes to pass therebetween, an arcuate guideway having inner and outersurfaces, and an arcuate toothed segment both adjacent the outerperiphery of said carrier and extending the length thereof; centeringrollers mounted on said carrier adjacent the inner periphery thereof,means providing that at least two of said centering rollers are radiallymovable with respect to the center of the welded pipes circumference anddisposed on opposite end portions of said carrier; cutting tool holdersdisposed on said carrier for movement to and from the weld bulge; amotor-operated carriage with means to be rigidly connected to a liftingmechanism of a vehicle used for raising and carrying the apparatus,which carriage including spaced support rollers and a driving gearwheel, said spaced rollers being disposed in engagement with the innerand outer surfaces of said arcuate guideway and said driving gear beingin driving engagement with the toothed segment of said carrier to rotatesaid carrier while said carriage remains immobilized.
 2. The apparatusaccording to claim 1, wherein said cutting tool holders are two innumber and they are disposed at diametrically opposite locations on saidcarrier.